In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
For example, communications networks may use remote radio units (RRUs) connected to centralized base band processing units, or network nodes, such as evolved NodeBs, that process the transmitted and received radio signals from the RRUs. The communication format often used for transmitting signals between the RRU and the eNodeB is the standardized common public radio interface (CPRI), defined by the CPRI co-operation, that allows digital transmission between RRUs and network nodes, such as evolved NodeBs. CPRI specification version 6.1 is currently available from www.cpri.info. The part of the communication network between the eNodeB and the RRUs are often referred to as fronthaul while the part of the communication network between the eNodeB and the evolved packet core (EPC) part of the communication network is referred to as backhaul.
FIG. 1 provides a schematic illustration of a communications network 100 where a wireless device no connects to one or more RRUs 120 that feed the signal as communicated with the wireless device no to a network node 200 over a fronthaul communication link being a wireless radio link 130. The network node 200 can use one or more RRUs 120 to communicate with the wireless device no and assemble data received from the wireless device 110.
The fronthaul network carries information representing the wireless signal that is communicated between RRUs and the wireless device, therefore the fronthaul part of the communications network must accommodate the full amplitude and phase information of the wireless signal communicated between the wireless device no and the network node 200. The bandwidth of a digitized version of this signal becomes much larger than the bandwidth used between the RRU 120 and the wireless device no for analog wireless transmission.
Hence there is a need for bandwidth efficient wireless fronthaul transport mechanisms.